Various types of physical therapy, including rehabilitative exercise, may employ externally applied, transcutaneous stimulation in the course of treating a subject. Typically, the stimulation comprises discrete electrical pulses generated by an external stimulator, and travel through associated wires to one or more electrode pairs placed on the skin adjacent a target location. In the case of exercise therapy, the electricity passing through the skin causes the targeted muscle fibers to activate or contract, even without voluntary control by the subject. Accordingly, such stimulation is frequently used in situations where the subject is incapacitated or otherwise unable to control function of the muscles, such as in the event of an injury to the brain or associated portion of the nervous system.
Despite the past use of electrical stimulation for providing therapy, certain limitations in the application of this technology and the results produced remain. For one, a pair of electrodes is typically associated with a single stimulation channel providing the electrical pulses to the targeted location. Thus, to simultaneously or even sequentially provide stimulation to different muscle groups or otherwise in a distributed fashion, pairs of electrodes must each be connected to a different channel of a stimulation source using individual wire for transmitting the pulses. Thus, for example, to stimulate three different muscle groups, three pairs of electrodes would be used, with each pair having an individual wire for transmitting the stimulation pulses from a three channel stimulator (and, to make the wires universal, they are typically made longer than necessary to reach a given body part). Aside from greatly increasing the cost and complexity, such wires may easily become tangled or damaged during the exercise movement.
In typical applications, the stimulation pulses delivered from the source are also infinitesimally small compared to the inter-pulse interval. For example, a given pulse may be active for less than 1,000 milliseconds for every 20,000 milliseconds of time that passes. Thus, there is a substantial amount of unused potential of the stimulation device while it waits to deliver the next pulse.
Accordingly, a need is identified for apparatus and methods that provide an improvement in delivering electrical stimulation to a subject in an efficient and effective manner. In particular, the apparatus would use a single transmission line per channel connected to serially arranged nodes, each associated with an electrode pair, to minimize the number of wires required. This would potentially allow for the application of stimulation to an unprecedented number of channels without significantly adding to the complexity or cost. Moreover, the apparatus would be capable of maximizing the potential of the stimulation device, which further enhances efficiency and reduces cost. Overall, a significant improvement over known past approaches would be realized.